Development of Single Crystals with High Thermoelectric Performance by Introducing Lattice Defects

Abstract

  Mg₂Sn has attracted attention as one of the efficient thermoelectric (TE) materials operating at 400 K~800 K. To improve its TE performance, Mg₂Sn single crystals (SCs) containing lattice defects were prepared. The lattice defects in Ga-doped and Li-doped Mg₂Sn SCs were investigated by single-crystal X-ray diffraction measurements and transmission electron microscope observations. The Seebeck coefficient, electrical conductivity, and thermal conductivity of the Ga-doped and Li-doped Mg₂Sn SCs were also measured. The lattice defects less affected the hole carrier transport, whereas they scattered phonons effectively. The dimensionless figure-of-merit zT of a Li-doped Mg₂Sn SC was higher than that of a Li-doped Mg₂Sn polycrystal, demonstrating that the potential of SCs with lattice defects can be a good candidate for TE applications.